Method of producing prefabricated forms of metals of high melting point



Oct. 1, 1957 A. R. GLOBUS METHOD OF PRODUCING PREFABRICATED FORMS OF METALS OF HIGH MEL-TING POINT Filed May 27, 1953 PROPORTIONIN'G PUMP INVENTOR AL FRED R. GLOBUS ATTORNEY United States Patent METHOD OF PRODUCING PREFABRICATED FORMS OF IVIETALS OF HIGH IVIELTING POINT Alfred R. Globus, Forest Hills, N. Y., assignor to United International Research, Inc., a corporation of New York Application May 27, 1953, Serial No. 357,863

8 Claims. (Cl. 75-10) This invention is a new and useful method of generating prefabricated forms of metals of high melting point. The metals referred to are those which melt at or above the melting point of iron and include iron, titanium, cobalt, chromium, nickel, tantalum and tungsten.

The invention will be fully understood from the following description read in conjunction with the drawing in which: 1

Fig. 1 is a vertical section of apparatus in which the invention may be carried out; and

Fig. 2 is a side View of a fragment of the showing in Fig. 1.

In accordance with my method I start with an oxide of the metal to be reduced and mix it with the amount of carbon stoichiometrically necessary for the reduction. Both the oxide and the carbon should be in very fine divided form and intimately mixed. The carbon must be electrically conductive and for this purpose I may use graphite, either natural or artificial, or the so-called metalloid coke. The mixture so formed must be held in some way in the prefabricated form desired during the reduction operation. The reduction is carried out by passing the form through an oscillating electrical field, in which it is heated to a temperature at which reduction proceeds but below the melting point of the metal produced. In general, there are two ways by which the mixture may be held in the prefabricated form desired during the reduction operation. The preferred method consists in bonding it with a bonding agent capable of holding it in the desired form up to the reduction temperature. This may be accomplished by making a stiff paste of the admixed materials with Water, molding the paste into the form desired, preferably under pressure, and then permitting it to gradually air-dry, followed by a final drying at a higher temperature to remove the last traces of moisture and thereby prevent decrepitation during the final reducing operation. Where the presence of a few percent of silicon in the ultimate product is not objectionable, the mixture may be bonded by the use of suificient waterglass to wet the components. Another method consists in the use of a core bonding composition, such as linseed oil, followed by baking the prefabricated form in a suitable oven to oxidize and set the composition.

One preferred application of my method consists in the making of prefabricated forms of metals for use as electrodes. In such case the mixture is bonded into cylindrical form and passed progressively through the oscillating electrical field. The preferred practice is to pass the form progressively upwardly through the field, and since the metal will be in the plastic range during the reduction operation, I find it advisable to apply some traction to the upper end of the form to prevent sagging or bending. The reduction should be carried out in a controlled atmosphere, and this atmosphere must be maintained surrounding the metal form produced until it is cooled to a temperature at which it is no longer spontaneously reactive. The controlled atmosphere may conexpression controlled atmosphere as herein used includes a vacuum.

Referring to the drawing, 1 designates a cylindrical shell terminating at its lower end in horizontal flange 2 and at its upper end in horizontal flange 3. Thelower end 4 is closed by plate 5 concentric with flange 2. The lower end 4 is provided with movable platen 6 carried by shaft 7 which enters the shell through stuffing box 8. Shaft '7 is in turn secured to piston 9 in cylinder 11. The lower end of the cylinder may be supplied with hydraulic fluid through pipe v12 controlled by valve 13, the amount of such fluid being regulated by proportioning pump 14. Parts 7 and 14 constitute a hydrostatic ram or lift adapted to gradually move the plate 6 upwardly within shell 1, or alternatively by suitable release of pressure, to permit the platen 6 to return to the position indicated in the figure. 15 indicates a coil of copper tubing adapted to be internally supplied with a coolant liquid from an external source (not shown). Provision is also made for supplying this coil with an oscillating electrical field from an external source (not shown), to thereby create an inductive heating field within the turns of the coil. The ends 16 and 17 of the coil enter the shell 1 through plate 18 by means of stufling boxes 19 and 20. Plate 18 is of non-conductive material to prevent local heating effects at the point Where the ends 16 and 17 pass through the same. Plate 18 is secured to manhole cover 21 carried by the side wall of shell 1. For the purpose of placing and adjusting materials within the shell, the shell is also provided on the opposite side with manhole 22 and cover 23. 24 indicates an elongated form of the mixture hereinabove described, which in this example is a cylinder of suitable dimensions for subsequent use as an electrode. The mixture may be held in this form by means of refractory shell diagrammatically indicated in part by the outline 25 and which may, for example, consist of a tube of fused silica. Preferably, however, no such support is provided and the mixture is held in the desired form by a preliminary bonding operation, such as that hereinabove described. Preferably the upper end 26 of the form 24 is grasped by a suitable holder 27, preferably of the quick detachable type. This in turn is secured to, and carried by, the shaft 28 which enters shell 1 through stufiing box 29 carried by top cover 31. Shaft 28 is connected to piston 32in cylinder 33. The shaft 28 enters the cylinder 33 through the stufiing box 34 carried by the bottom. plate 35. Provision is made for the controlled introduction of a hydrostatic fluid to the lower end of cylinder 33 through pipe 36, controlled by valve 37. Parts 3437 constitute a hydrostatic lift adapted to move the holder 27 controllably upward, thereby exerting traction on the upper end of the form 24. The lift is secured in spaced relationship to the cover 31 by means of the I-beams 41 and 42. The I-beam 43 rests on, and is secured to, the upper end 44 of cylinder 33 by angles 45 and 46 (Fig. 2). Beam 43 defines'a central aperture 47 which may be engaged by a suitable lifting hook 48. Hydrostatic fluid may be supplied to cylinder 33 through pipe 51 controlled by valve 52 by proportioning pump 14.

Gas may be passed into the lower end of shell 1 through pipe 53 controlled by valve 54 and conducted away through pipe 55 controlled by valve 56. Alternatively the valve in one of these pipes may be closed and vacuum applied to the system through the other pipe.

In operation, with the platen in the position indicated in Fig. 1, the entire top of the apparatus is removed by lifting cylinder 33 and the associated cover 31 together with shaft 28 and holder 27. With this part of the apparatus out of the 'way, the form to be reduced is lowered into position on the platen 6. The upper part of the apparatus is then replaced, and with the cover 23 removed, the holder 27 is made up to engage the upper end'26-of the form 24. The'cover 23 is -then=replaced and a suitable gas, either nitrogen or an inert gas, depending upontheparticularoxidetobe reduced, is passed in through pipe 53 until all-or substantially all of-the oxygen in the system has been displaced through pipe 55. Current is then applied ,to thecoil 15' and as soon as the-upper end of the form '24 has been heated to and held at a reduction temperature for a length of time sufficient to substantially complete reductionin theupper end of the-mass, equal amounts of fluid are supplied by the proportioning pump -14through pipes 12 and 36 to thelower ends of cylinders 11 and 33. The amount of fluid is controlled so that reduction will be substantially complete as the form 24 moves upwardly through the oscillating electrical field produced by coil 15. During this phase of the operation'holder 27 exertssufiicient traction on the form 24 to prevent it from sagging'or bending. Gas is continuously passed in through pipe 53 to sweep out the carbon monoxide as formed.

When platen 6 reaches the upper limit of travel, the current is discontinued. It is impractical in this type of operation to carry the reduction completely to the ends of the form although it may be carried completely to the lower end, provided a pillow of refractory material is interposed between'the lower endof form 24 and platen 6.

Following the completion of the reduction-operation, platen 6 and holder 27 are returned tothe position indicated in Fig. l and the non-oxidizing atmosphere is maintained in shell 1 until the form of reducedmetal has cooled sufficiently to permit its handling. At this stage the cover 23 isremoved, the holder 27 is disconnected from the upper end of the form and the top of the apparatus is removed, thereby permitting the removal of' the finished, prefabricated form of reduced metal restingon platen 6. Any unreduced ends of the form 24 are then severed, whereupon the cylinder of-metal is ready for use. It may, if desired, be subjected to an additional forging or swaging operation to reduce porosity and increase density and tensilestrength.

-I claim:

1. Method of generating prefabricated forms'of metals of high meltingpoint, which comprises forming a mixture of the oxide of such a metal with the amount of electrically conductive carbon necessary for reduction, holding such mixture in predetermined form andheating the mixture in such form by the application thereto of an oscillating electrical field, to a temperature-at-Which reduction proceeds but below themelting point of said metal.

2. Method according to claim 1 in which the mixture is held in predetermined form by mixing it with a bonding agent capable of holding the mixture in such form up to at least the temperature of reduction.

3. Method according to claim 1 in which the mixture is vheld .in predetermined form by retaining it in a nonconductive refractory shell.

4. Method of generating prefabricated forms of metals of high melting point, which comprises forming a mixture of the oxide of such a .metal with the amount of electrically conductive carbon necessary for reduction, holdingsuch mixture in predetermined form and heating the mixture in such form by passing the same progressively through an oscillating electrical field in which it is heated, to a temperature at which reduction proceeds but below the melting point ofsuch metal.

5. Method of generating prefabricated forms of metals of high melting point, which comprises forming a mixture of the oxide of such a metal with the amount of electrically conductive carbon necessary for reduction, holding such mixture in predetermined form, heating the mixture in such form by the application thereto of an oscillating electrical ,field,;to a temperature at which reduction proeeedsflbut below the melting point of said.

metal, thereby producing amass of such metal in said prefabricated form, and thereafter cooling said mass while maintaining a nonroxidizing atmosphere surrounding-gthe same.

6. Method of generatingprefabricated forms of metals of high melting point, which, comprises forming-a mixture of the ;0x id e of such ametal with .the amount of electrically conductive carbon necessary for reduction, holding such -rnixtur e; in elongated form and heating the mixture in such form to a temperature at which reductien'proceeds-but helowthe melting point of such metal, ypassi g .flle'tsame progressively upwardly through an oscillating electrical field.

7. Method of generating. prefabricatedfiorms of metals of high melting point, which comprises forming a mixture of theoxide of such a metal with the amount of electrically conductive carbon necessary for reduction, holding such mixture in elongated form by mixing it with a'bonding agent capable of holding the mixture in such form up to at least-the temperature of reduction, heating the mixture in such form to a temperature at which reduction-proceedsgbut belowthe melting point of said-metal, bypassing said form progressively upwardly throughan oscillatingfield while exerting traction on the upper end of saidiorm.

8. =Method according tool-aim 7 followed bycooling the prefabricated; form ,ofmetal tso produced while maintaining .a nomoxidizing atmosphere surrounding the same.

References Cited in the'filetof this patent UNITED STATES PATENTS 133,099 iI-Iay 'Nov. 19, 1872 1,714,767 Cousin May 28, 1929 2,124,262 Samuelson et al. July 19, 1938 FOREIGN JPATENTS 645,030 Great Britain Oct. 25, 1950 .t. in 

4. METHOD OF GENERATING PREFABRICATED FORMS OF METALS OF HIGH MELTING POINT, WHICH COMPRISES FORMING A MIXTURE OF THE OXIDE OF SUCH A METAL WITH THE AMOUNT OF ELECTRICALLY CONDUCTIVE CARBON NECESSARY FOR REDUCTION, HOLDING SUCH MIXTURE IN PREDETERMINED FORM AND HEATING THE MIXTURE IN SUCH FORM BY PASSING THE SAME PROGRESSIVELY THROUGH AN OSCILLATING ELECTRICAL FIELD IN WHICH IT IS HEATED, TO A TEMPERATURE AT WHICH REDUCTION PROCEEDS BUT BELOW THE MELTING POINT OF SUCH METAL. 